RESIST

Overview

RESIST is a computer program that enables designers to determine the numbers and sizes of vertical lateral load resisting elements in a building. RESIST undertakes structural analyses like structural engineers do for preliminary designs.

RESIST Limitations

RESIST is intended primarily as an educational tool for Architecture and Civil Engineering students to initially size vertical elements to resist wind and earthquake loads. However, RESIST may be useful during an actual building design. At the conceptual or preliminary design stage, RESIST can help initial sizing and investigating different structural options, helping facilitate discussion between architect and structural engineer. Once a conceptual design has been formulated, the structural engineer will carry out a full preliminary design, where ALL assumptions and initial sizes from RESIST are re-evaluated for accuracy and appropriateness. RESIST cannot be used as a substitute for a complete preliminary design by a structural engineer. Final design will follow from the structural engineer’s preliminary design, and the results from RESIST should not influence that final stage of design.

Floor diaphragm adequacy is not evaluated by RESIST. It assumes that rigid roof and floor diaphragms have sufficient strength to transfer loads to all vertical resisting elements. The floor plan editor allows non-rectangular floor diaphragms, which if highly irregular or with large penetrations, will require careful design by a structural engineer.

Structural connections within the resisting elements and the rest of the building are not considered by RESIST. Connections are critical to the performance of the building. They are assumed to have adequate strength.

The design of all structural systems, including steel eccentric braced frames (EBFs) requires careful design to ensure they behave as expected. RESIST only carries out an initial assessment of the design of the EBF. Many other aspects will require design by a structural engineer.

RESIST uses an elastic approach for evaluating torsion effects. Generally, torsion should be evaluated by taking into account inelastic deformations.

The lateral resisting systems provided by RESIST are only some of the possible choices currently available. Newer technologies, such as buckling-restrained braced frames, base-isolation and other systems may be a suitable for a building. A structural engineer will provide guidance.

Fire protection of members is not considered by RESIST.

For further limitations, an outline of the scope of RESIST and full technical information, refer to further documentation in the Help section.

Using RESIST

Users begin by defining the height and plan dimensions of a building, using the floor plan editor, and then choose either ‘heavy’, ‘medium’ or ‘light-weight’ construction for walls, floors and roof. They select the building importance factor and the seismic zone from an on-screen map before inputting several factors that enable the program to calculate wind loads.

In the next phase of the design process, users choose one lateral load resisting system for each orthogonal building direction. For example, moment frames might resist transverse loads while structural walls provide longitudinal resistance. Most structural systems are possible in reinforced concrete, steel and timber. After choosing the numbers of vertical elements in each direction and estimating their size, users refer to the ‘Results’ screen that displays bar graphs showing how key structural indicators, like bending strength and drift compare with code requirements. If structural actions exceed 100% of code values the structure is under-designed. This suggests that member sizes should be enlarged or more members provided.

Users iterate towards a solution while a 3-D graphic enables them to see the structure they are designing. After completing an acceptable design, users can access more specialized information, for example, sizes of foundations and maximum sizes of openings in structural walls. A simple report that includes an image of the building and structure as modelled can be included in a structural report. Users choose between a brief Architectural Report, or a more detailed Engineering Report.

A huge benefit of the program is that it enables users to quickly explore many different structural solutions before arriving at the one that best integrates structure with architectural requirements.

Disclaimer

Although NZSEE hosts the RESIST software on its website on behalf of the authors, this does not constitute endorsement or certification of its content. Full liability and responsibility for RESIST’s application and accuracy lies with the user alone.

The New Zealand Society for Earthquake Engineering Inc.

A collaborating technical group of the Institution of Professional Engineers New Zealand